1. Field of the Invention
The present invention relates to vibrating plates according to the preambles of patent claims 1 and 3.
2. Description of the Related Art
Vibrating plates for soil compaction are known in many embodiments. Such vibrating plates have in common that they are made tip in principle of a lower mass and an upper mass that is decoupled in terms of vibration from the lower mass via a spring device. The lower mass has a soil contact plate that acts on the soil and a vibration exciter device fastened thereon. An essential component of the upper mass is a drive motor that drives the vibration exciter device on the lower mass in a suitable manner (mechanically, hydraulically). Known one- and two-shaft exciters are examples of suitable vibration exciters.
FIG. 1 shows a perspective view of a vibrating plate having a drawbar control device, known from DE 102 26 920 A1.
On a soil contact plate 1, a vibration exciter 2 is attached that is driven by a drive 3, e.g. an internal combustion engine. Soil contact plate 1 and vibration exciter 2 form a lower mass, while drive 3, together with a frame 4 and a cover 5, are considered to be part of an upper mass. The upper mass is vibrationally decoupled from the lower mass with the aid of intermediately connected spring devices (not shown in FIG. 1).
Cover 5 of the upper mass has attached to it a drawbar 6 that has a drawbar boom 7 that ends in a drawbar head 8 (shown only schematically). Two control handles 9 are mounted pivotably on drawbar head 8. With the aid of control handles 9, hydraulic valves can be controlled via which the phase position of rotating imbalance masses or imbalance shafts in vibration exciter 2 can be altered. In this way, the direction of a resultant force vector produced by the imbalance masses in vibration exciter 2 can be adjusted in a known manner in order to achieve forward and backward travel of the vibrating plate.
In addition, control handles 9 are constructed with enough mass that the operator can draw and pull on them in such a way as to alter the direction of the vibrating plate during operation.
A travel mechanism 10 is used only for transporting the vibrating plate, and does not have any function during operation.
In large, steerable vibrating plates, it is possible for at least one of the imbalance shafts to be axially divided in order to control different imbalance masses in such a way as to produce a yaw moment about a vertical axis of the vibrating plate, in order to enable steering of the plate. In smaller, lighter vibrating plates, usually a drawbar is provided with which the operator can guide the vibrating plate. Here, the vibration exciter produces not only the vibrations that compact the soil, but also a force component in the forward or backward direction. Correspondingly, handles are provided on the drawbar via which the operator can control the vibration exciter device in the desired manner in order to achieve the desired direction of travel. The steering and guiding of the vibrating plate is accomplished by the operator by moving the end of the drawbar with the aid of the control handles or additional handles.
Above all in large, heavy vibrating plates, it has become standard to provide a remote control with the aid of which the operator can control the vibrating plate without being located in its immediate vicinity. This is useful above all because heavy vibrating plates introduce very strong vibrations into the soil that can have a harmful effect on people standing directly adjacent to the plate. In addition, the danger to the operator as a result of contact with the moving vibrating plate is less, due to the greater distance.
However, in practice it has turned out that the vibrating plates execute a wobbling, random movement due to the strong vibrations and accidental counterforces that sometimes occur due to the soil being compacted. Thus, it is often difficult to guide the vibrating plate precisely in a straight line over a longer path. Likewise, in practice it requires a very high degree of concentration on the part of the operator if the vibrating plate is to be guided along a curve. Correspondingly, the operator constantly has to carry out steering corrections, which often do not achieve the desired result due to the very indirect effect of the operator's control commands. Differing from, for example, vibrating rollers, the operator of a vibrating plate cannot exert an immediate influence on the forward drive or a corresponding steering device. Rather, the operator can only influence the position of the imbalance masses in the vibration exciter, in the hope that this will result in corresponding centrifugal forces that draw the vibrating plate in the desired direction.
Thus, the remote control offers the operator only a very limited degree of sensitivity. In particular in cases in which the soil compacting requires a high degree of precision, for example along a curb wall, the operator will attempt to guide the vibrating plate manually using the drawbar. However, remote-controllable vibrating plates have in most cases no guiding drawbar, or one having only a rudimentary construction, often having a short handle that makes it difficult to guide the vibrating plate manually.
One solution to this problem could be to provide a hybrid control device in which a vibrating plate is equipped with a drawbar controlling in the classical manner, in which the operator can manually guide the drawbar using control handles and can control the vibration exciter via the control handles. In addition, a known remote control is provided that is used if the operator does not wish to guide the drawbar. A disadvantage of this hybrid controlling is that it requires a very high constructive expense, because on the one hand two sets of command devices must be present (control handles on the drawbar end and control elements at a transmitter of the remote control). In addition, the transmitter is a separate part of the control device that has to be housed on the vibrating plate when it is not being used, so that it will not be lost.
In a vibrating plate manufactured by applicant, having the type designation “Wacker DPU 7060,” instead of a drawbar a guide bow is fastened to the upper mass of the vibrating plate. Instead of operating elements, the guide bow has a holder in which the transmit unit of a cable-connected remote control can be used. The controlling of the vibration exciter takes place exclusively via the operating elements of the cable-connected remote control.
From DE 199 13 074 A1, a soil compacting device is known in which at the end of a drawbar an operating element is attached that is capable of being moved relative to the drawbar. The respective position of the operating element is acquired by a sensor device that forwards a corresponding signal to a hydraulic control unit for a vibration exciter.
In US 2004/0022582 A1, a vibrating plate having a radio remote control device is indicated. A joystick for inputting control commands is provided on the transmit unit of the remote control device.